Who said it’s not terror related?
Merseyside police said that they did not believe it was terror related (it's in press release of 30 July) but have also said that counter-terrorism police were involved in the investigation.
I realise that's not slam dunk "it isn't" but I do not think they would have included any statement about it not being terrorism in the press release if that were not overwhelmingly likely to be the case
Edited to add: everything else about the case (including any prosecution theories on his motivation) are indeed being withheld in line with normal procedure for all cases sub judice.